Monday, 30 April 2012

While I'm waiting for the parts to arrive for me to build the real wifi controller board, I found this temporary solution in the local computer shop today.

Vonets VAP11G

It's a wifi ethernet bridge, and at around $25 I thought it was worth a shot. Sadly I can't put it to use tonight as the little CD only has software to configure it from a windows machine and frankly, I don't have any of those laying around..

Wednesday, 25 April 2012

A few people have asked me to post the source code. Here it is. Even though I have been programming for years in various database and IBM mainframe languages, I've never done much C, so feel free to send me a few tips. I'm not sure why, for example, it works only when ctTime and buffer[21] are declared outside of the subroutine they're used in??

It talks about oAuth and fun things like this, but I discovered that you don't have to authenticate if you use the xml private address found on your calendar settings page.

Getting the Private address

Now you can use any of the read-only API features as GET requests from google calendar. On the mBed I set the realtime clock using NTP and then format the time in RFC 3339, then the time plus one minute. It will return an XML of a event that is current.

So far so good. The final feature I wanted was the ability to enter events using my smart phone. Here's the time where I'm going to have to mention that I don't have an Android or open source smart phone, I carry an iPhone... *hides*

There were a few websites that I found useful getting multiple google calendars to sync with my phone's calendar. Have a read and you'll work it out.

Finally, I've ordered some more bits to make the mBed connect via my wireless network as I don't currently have a wired one. Right now I'm using a computer as a wireless bridge and connecting the mBed using a crossover cable. These parts should arrive early next week.

In the video posted below, I was controlling the heater by simply cutting the power supply to it. This was good because it meant that I hadn't played around with the built in safety features, but bad because it beeped every time the power cycled. Time to break out the screwdrivers!

The built in controller

The built in controller is fairly simple and I quickly figured out which was the signal between the two boards that caused the relay to switch. I then had a think about if it was safe to drive that relay myself, or should I be putting a second on in series with it, meaning I've got a fail safe with the on board temperature controller if my controller forgot to switch it off. I can wind the on board one up to a temperature at the highest level that I'll ever want, and that is as hot as the room will get in the event of a failure.

40A Solid State relay

I discovered when I went to my local electronics shop that they had some rather grunty solid state relays available for around $45 each. I grabbed a handful of 40A AC ones and one 100A DC for another project.

It fits in the space!! :)

As I said, I wired it in series with the existing controller for safety reasons. I'm not much of a C programmer so I figured this was the best option.

I've been thinking about what automated features I'd like in my new house which I hope to build in the coming year. This is the first of many ideas, programming the schedule and temperature of my heating using Google Calendar!

I'm using an mBed in this video, but I've also got another board which is being designed by my friend Stu. Watch this space

I'll post some photos soon, tomorrow I'll be pulling the heater apart to wire it up properly. In the video you'll notice a 'beep' when it cuts in and out. This is not a desirable feature which is about to get fixed.

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About Me

When you're building a house, it's a clean slate. Hopefully I can get all my ideas together and make sure all the features I want are built in.
Subtle automation is the key, I don't want to have complicated technology, so comfortable, sensible and intuitive is the order of the day.